Flow emitter units have now been known and used for many years, particularly in irrigation, for ensuring the drip irrigation of crops. To this end, many proposals have been put forward, some of which have been employed in practice, for suitable mechanisms, known as emitter units, which ensure that a supply irrigation flow is delivered to the crops to be irrigated in the form of a drip having a specified drip output rate. It is known to be desirable with such emitter units that the unit should be capable of supplying the drip outflow at the required rate and, at the same time, should be minimally susceptible to blockage as a result of grit or other impurities to be found in the irrigation water. It is, of course, desirable that emitter units which are designed to satisfy these requirements should also be capable of ready and economical production and ease of use.
To this end, there have been many prior proposals which have attempted to fulfill these requirements to a lesser or greater degree. Among these prior proposals is the subject of our prior U.S. Pat. No. 4,060,200, in accordance with which the emitter unit was provided with a flowduct of specific shape and having relative dimensions lying within a specific range. The proposals made in our prior patent were, in fact, incorporated in emitter units which have been manufactured and sold throughout the world with a considerable degree of success.
The present invention allows for the production of emitter units having radically improved performance characteristics.